The present invention relates to a device information management system, and particularly to such a system for managing devices connected to a network.
Conventionally, there has been known a program called as a status monitor, which is executed on a computer to investigate and/or manage the status (e.g., on-line/off-line, busy, error, etc.) of each device (e.g., a printer or an MFP (multi-function peripheral) having a printer function connected to the computer. There has also been known a program called as a maintenance tool, which is executed on a computer to manage maintenance information (e.g., remaining amount of toner or ink, remaining amount of a recording sheet, a term for exchanging a photosensitive drum, etc.) of an imaging device connected to the computer.
The conventional status monitor and maintenance tool have been executed locally. Recently, however, a plurality of computers are interconnected through a network, and therefore, it is desirable that the status and/or maintenance information of devices connected to respective computers are managed at a particular computer (e.g., one used by a system administrator).
In response to the above-described desire, a central management system has been suggested in Japanese Patent Provisional Publication No. P2000-293324A. In this publication, each computer on a network obtains status/maintenance information of a locally connected printer, and transmits the thus obtained information to another computer connected to the network.
Specifically, according to the publication, an operational status of an imaging device is monitored, and when the operational status is changed, the changed status is obtained, and is transmitted to another computer which is connected to the network. Such a procedure is called as a trapping procedure in the publication. The publication also provides a response to request procedure which obtains the status of the imaging device immediately when a request for such information is received from another computer through the network, and provides the obtained status information to the computer which has issued the request.
In the conventional information management system as exemplified above, the computer attempts to obtain the latest status/maintenance information from the local imaging device when the trapping procedure or the request procedure is executed. According to such a system, if the response is not provided by the imaging device, the computer is unable to transmit the information immediately. That is, due to the delay of the response form the imaging device, transmission of the information from a requested computer to a requesting computer is delayed.
Specifically, for obtaining information from the imaging device, a method of transmitting a command described using a PJL (Printer Job Language) to the imaging device, and reading back (receiving) the information transmitted by the imaging device in response to the PJL command has been known.
According to the above method, the PJL command is treated as a printing job in the imaging device. That is, the PJL command is added to a print data queue, and then processed as one of a plurality of printing jobs in the print data queue. Therefore, if a relatively large number of printing jobs have already been included in the print data queue or a relatively large number of print jobs have previously been added in the print data queue, the PJL command will not be processed until all the print jobs are processed. In such a case, the response to the PJL command will not be transmitted from the imaging device to the computer immediately, and the information will not be provided immediately.
For another example, due to running out of the recording sheet, the imaging device may turn to a busy status. In such a case, the print jobs in the print queue cannot be processed, and thus, the PJL command will not processed either. Also in this case, the response to the PJL command will not be transmitted from the imaging device to the computer, and the information will not be provided to another computer immediately. Additionally, in such a case, the PJL command remains in the print data queue as one of the print jobs. If the user of the printer (or the computer to which the printer is connected) does not know the reason why the PJL command was issued, the user may consider that an unknown print job is included in the print data queue. In such a situation, the user may not determine whether the job (PJL command) should be remained or deleted. In particular, since a computer virus may generate such a job, the unknown job remained in the queue causes an uneasy feeling to the user.
As indicated, according to the conventional method, in some cases, the response from the imaging device may not be obtained for a relatively long period, and in such a case, transmission of the information of the imaging device may not be done immediately.
Further, the conventional system may cause problem since a print job that cannot be recognized by the user may be added and remained in the print data queue.